Method for calculating average temperature rise of winding of oil-immersed transformer based on respiration characteristic parameters
By installing sensors to collect data and calculate breathing characteristic parameters, the accuracy and calculation complexity of winding temperature rise measurement of oil-immersed transformer is solved, and efficient and low-cost winding temperature rise calculation is achieved.
Patent Information
- Application Number
- CN202510477794.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-08-01
AI Technical Summary
The prior art has problems of insufficient measurement accuracy and high computational complexity in the measurement of temperature rise of the oil-immersed transformer, especially traditional methods are susceptible to errors, while emerging methods are high in calculation costs and insufficient in efficiency improvement.
By installing flow sensors, pressure sensors, temperature sensors and humidity sensors, the flow, pressure difference, temperature and humidity data of the transformer are collected, the breathing characteristic parameters, dynamic impedance coefficients and silicone life decay coefficients are calculated, and the average temperature rise of the winding is finally calculated.
High-precision and low-cost winding temperature rise calculations are realized, simplifying the calculation steps and improving the calculation efficiency.
Smart Images
Figure CN120405507A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of transformers and relates to a method for calculating the average temperature rise of the windings of an oil-immersed transformer based on breathing characteristic parameters. Background Art
[0002] Oil-immersed transformers are indispensable equipment in the power system, and their function is mainly to control the rise or fall of voltage. The temperature rise monitoring of transformer windings is crucial for the safe operation of oil-immersed transformers. Traditional methods mainly rely on mechanical winding thermometers for direct measurement, but they are easily affected by factors such as ratio error and electrothermal loss, resulting in insufficient measurement accuracy; emerging methods mainly rely on various fluid mechanics models, such as multiphase flow models or fluid-structure-thermal coupling models, set heat sources and boundary conditions, and use numerical calculation methods for simulation calculation to achieve accurate measurement, but the calculation steps are quite complex and the calculation cost is quite high. Although there are already optimization methods such as the dynamic mode decomposition - adaptive variable step size method to improve the calculation efficiency. However, these methods are still insufficient in improving the calculation efficiency.
[0003] In fact, during the operation of the transformer, the temperature rise of the transformer windings will also cause changes in the internal oil temperature, which will in turn cause the volume of the oil to expand or contract, and ultimately cause gas exchange between the transformer and the outside atmosphere, that is, the breathing phenomenon of the transformer. Therefore, it is necessary to establish the connection between the breathing phenomenon and the winding temperature rise, that is, to calculate the average temperature rise of the windings of the oil-immersed transformer based on the breathing characteristic parameters. Summary of the Invention
[0004] The present invention proposes a method for calculating the average temperature rise of the windings of an oil-immersed transformer based on breathing characteristic parameters. It is characterized by including the following steps:
[0005] S1. Install a flow sensor, a pressure sensor, a temperature sensor, and a humidity sensor in a maintenance-free breather;
[0006] S2. Collect the test data of the flow rate, pressure difference, temperature, and humidity required under the rated and actual working conditions of the transformer;
[0007] S3. Calculate the required breathing characteristic parameters, the dynamic impedance coefficient of the transformer, and the silica gel life attenuation coefficient of the breather;
[0008] S4. Calculate the average temperature rise of the transformer windings.
[0009] In step S1, the maintenance-free breather can perform drying and regeneration treatment on the moisture-saturated silica gel, and can record the regeneration times, which is used as the silica gel cycle times m. The flow sensor and the temperature sensor need to be installed at the connection flange of the transformer breather, and the pressure sensor and the humidity sensor need to be installed at one place each at the inlet and outlet of the transformer breather to form a set of sensors.
[0010] In step S2, for collecting the flow rate, pressure difference, temperature, and humidity data of the transformer under rated conditions and actual conditions, the flow sensor should record, in chronological order, the flow rate values recorded at the k-th measurement before reaching the steady-state operation under the rated conditions and actual conditions of the transformer, denoted as A k0 and A k respectively; the temperature sensor should record the temperatures of the respective gases under rated conditions and actual conditions, denoted as T0 and T; the humidity sensor only needs to record the gas humidities of the respective inflows and outflows of the breather under actual conditions, denoted as H in and H out respectively; the pressure sensor should obtain the pressure difference by subtracting the pressure measured by the sensor at the outlet from the pressure measured by the sensor at the inlet, and thus record the pressure differences of the respective rated conditions and actual conditions as P0 and P.
[0011] In step S3, the required breathing characteristic parameters to be calculated include the maximum breathing rate, total breathing volume, and the time required to reach the maximum breathing volume when the oil-immersed transformer reaches the steady-state operation under actual conditions, as well as the total breathing volume when the transformer reaches the steady-state operation under rated conditions. The solution formulas are as shown below:
[0012]
[0013] In the formula, Q is the total breathing volume of the transformer when reaching the steady-state operation under actual conditions, Q0 is the total breathing volume of the transformer when reaching the steady-state operation under rated conditions, v max is the maximum breathing rate of the transformer when reaching the steady-state operation under actual conditions, t max is the time required for the transformer when reaching the steady-state operation under actual conditions, k is the measurement serial number, n is the total number of measurements within the measurement time, A k is the flow rate value recorded at the k-th measurement, Δt k is the time required for the k-th measurement.
[0014] In step S3, for calculating the dynamic impedance coefficient of the transformer, the formula is as shown below:
[0015]
[0016] In the formula, Z0 is the dynamic impedance coefficient at room temperature of 298K, Z is the dynamic impedance coefficient at the current temperature T, μ is the air dynamic viscosity of the gas at the current temperature T, μ0 is the air dynamic viscosity of the gas at room temperature of 298K, both μ and μ0 are obtained based on the Sutherland formula using the temperature, P and P0 are the pressure differences under actual conditions and rated conditions respectively, ε is the porosity of the silica gel tank, and L is the equivalent length of the gas flow path.
[0017] In step S3, the calculation of the breather silica gel life attenuation coefficient is shown by the following formula:
[0018]
[0019] In the formula, η is the breather silica gel life attenuation coefficient, m is the number of cycles of the silica gel, S is the equivalent cross-sectional area of the breather air flow path, H in is the humidity of the incoming gas, and H out is the humidity of the outgoing gas.
[0020] In step S4, the calculation of the average temperature rise of the transformer winding is shown by the following formula:
[0021]
[0022] In the formula, ΔT is the average temperature rise of the winding, M is the mass of the transformer oil, ρ is the density of the transformer oil, and α is the expansion coefficient of the transformer oil;
[0023] In the formula, k is a dimensionless proportional correction coefficient, k = 22069.29; T C is the temperature correction coefficient, and T C = 260.74 K. Description of the Drawings
[0024] Figure 1 is a flowchart of a method for calculating the average temperature rise of the winding of an oil-immersed transformer based on respiratory characteristic parameters; Detailed Embodiments
[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.
[0026] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.
[0027] Embodiment 1
[0028] Taking an oil-immersed transformer of model S11-M-1250 / 10 as an example, its relevant physical property parameters are shown in the following table;
[0029] Table 1 Transformer Physical Property Parameters
[0030]
[0031] Step 1: Install a flow sensor, a pressure sensor, a temperature sensor, and a humidity sensor at the maintenance-free breather. The maintenance-free breather can dry and regenerate the moisture-saturated silica gel and record the regeneration times, which is used as the silica gel cycle times m. At the same time, the flow sensor and the temperature sensor need to be installed at the connection flange of the transformer breather, and the pressure sensor and the humidity sensor need to be installed at one place each at the inlet and outlet of the transformer breather to form a set of sensors.
[0032] Step 2: Collect the flow rate, pressure difference, temperature, and humidity data under the rated and actual operating conditions of the transformer. The flow sensor should record the flow rate values recorded at the k-th measurement before reaching the steady-state operation under the rated and actual operating conditions of the transformer in chronological order, denoted as A k0 and A k respectively; the temperature sensor should record the temperatures of the respective gases under the rated and actual operating conditions, denoted as T0 and T; the humidity sensor only needs to record the gas humidities flowing into and out of the breather under the actual operating conditions, denoted as H in and H out respectively; the pressure sensor should obtain the pressure difference by subtracting the pressure measured by the sensor at the outlet from the pressure measured by the sensor at the inlet, and thus record the respective pressure differences under the rated and actual operating conditions as P0 and P.
[0033] Step 3: Calculate the required breathing characteristic parameters, including the maximum breathing rate, total breathing volume, and time required to reach the maximum breathing volume when the oil-immersed transformer reaches the steady-state operation under the actual operating conditions, and the total breathing volume when the transformer reaches the steady-state operation under the rated operating conditions. The solution formulas are as shown below:
[0034]
[0035] In the formula, Q is the total breathing volume of the transformer when reaching the steady-state operation under the actual operating conditions, Q0 is the total breathing volume of the transformer when reaching the steady-state operation under the rated operating conditions, v max is the maximum breathing rate of the transformer when reaching the steady-state operation under the actual operating conditions, t max is the time required for the transformer when reaching the steady-state operation under the actual operating conditions, k is the measurement serial number, n is the total number of measurements during the measurement time, A k is the flow rate value recorded at the k-th measurement, Δt k is the time required for the k-th measurement.
[0036] Step 3: Calculate the dynamic impedance coefficient of the transformer. The formula is as shown below:
[0037]
[0038] In the formula, Z0 is the dynamic impedance coefficient at room temperature of 298K, Z is the dynamic impedance coefficient at the current temperature T, μ is the aerodynamic viscosity of the gas at the current temperature T, μ0 is the aerodynamic viscosity of the gas at room temperature of 298K, both μ and μ0 are obtained based on the Sutherland formula using temperature, P and P0 are the pressure differences under actual working conditions and rated working conditions respectively, ε is the porosity of the silica gel tank, and L is the equivalent length of the gas flow path.
[0039] Step 3: Calculate the attenuation coefficient of the silica gel life of the respirator. The formula is as follows:
[0040]
[0041] In the formula, η is the attenuation coefficient of the silica gel life of the respirator, m is the number of cycles of the silica gel, S is the equivalent cross-sectional area of the gas flow path of the respirator, H in is the humidity of the incoming gas, and H out is the humidity of the outgoing gas.
[0042] Substitute the physical property parameters of the transformer described in Table 1 into the formula in Step 3, and the following data can be obtained as shown in the following table:
[0043] Table 2 Test and calculation data
[0044]
[0045] Step 4: Calculate the average temperature rise of the transformer winding. The formula is as follows:
[0046]
[0047] In the formula, ΔT is the average temperature rise of the winding, M is the mass of the transformer oil, ρ is the density of the transformer oil, and α is the expansion coefficient of the transformer oil.
[0048] In the formula, k is a dimensionless proportional correction coefficient, k = 22069.29; T C is the temperature correction coefficient, and T C = 260.74K.
[0049] Substitute the data shown in Table 1 and Table 2 into the calculation formula of the average temperature rise of the transformer winding in Step 4. After calculation, the average temperature rise of the transformer winding ΔT = 292.58K is obtained.
[0050] The above content is only an explanation of the structure of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific structure. As long as they do not deviate from the structure of the invention or exceed the scope defined by this claim book, they should fall within the protection scope of the present invention.
Claims
1. A method for calculating the average temperature rise of the winding of an oil-immersed transformer based on respiratory characteristic parameters, characterized in that, It includes the following steps: S1. Install a flow sensor, a pressure sensor, a temperature sensor, and a humidity sensor in the maintenance-free breather; S2. Collect the test data of the flow rate, differential pressure, temperature, and humidity required under the rated working condition and the actual working condition of the transformer; S3. Calculate the required breathing characteristic parameters, the dynamic impedance coefficient of the transformer, and the life attenuation coefficient of the breather silica gel; S4. Calculate the average temperature rise of the transformer winding.
2. The method for calculating the average temperature rise of the winding of an oil-immersed transformer based on respiratory characteristic parameters according to claim 1, wherein, In step S1, the maintenance-free breather can perform drying and regeneration treatment on the moisture-saturated silica gel, and can record the regeneration times, which is used as the silica gel cycle times m. For the flow sensor, pressure sensor, temperature sensor, and humidity sensor, the flow sensor and temperature sensor need to be installed at the connection flange of the transformer breather, and the pressure sensor and humidity sensor need to be installed at one place each at the inlet and outlet of the transformer breather to form a group of sensors.
3. The method for calculating the average temperature rise of the winding of an oil-immersed transformer based on respiratory characteristic parameters according to claim 1, wherein In step S2, for the data acquisition of the flow rate, differential pressure, temperature, and humidity of the transformer under the rated condition and the actual condition, the flow rate sensor should record, in chronological order, the flow rate values recorded at the k-th measurement before reaching the steady-state operation under the rated condition and the actual condition of the transformer, denoted as A k0 and A k respectively; the temperature sensor should record the temperatures of the respective gases under the rated condition and the actual condition, denoted as T0 and T respectively; the humidity sensor only needs to record the gas humidities of the respective inflows and outflows of the breather under the actual condition, denoted as H in and H out respectively; the pressure sensor should subtract the pressure measured by the sensor at the outlet from the pressure measured by the sensor at the inlet to obtain the differential pressure, and thus record the differential pressures of the respective rated condition and the actual condition as P0 and P respectively.
4. A method for calculating the average temperature rise of the winding of an oil-immersed transformer based on respiratory characteristic parameters according to claim 1, characterized in that In step S3, the calculation of the required breathing characteristic parameters includes the maximum breathing rate, total breathing volume when the oil-immersed transformer reaches the steady-state operation state under the actual working condition, the time required to reach the maximum breathing volume, and the total breathing volume when the transformer reaches the steady-state operation state under the rated working condition. The solution formula is shown as follows: In the formula, Q is the total breathing volume of the transformer when it reaches the steady-state operation under actual working conditions, Q0 is the total breathing volume of the transformer when it reaches the steady-state operation under rated working conditions, v max is the maximum breathing rate of the transformer when it reaches the steady-state operation under actual working conditions, t max is the time required for the transformer to reach the steady-state operation under actual working conditions, k is the measurement serial number, n is the total number of measurements during the measurement time, A k is the flow value recorded at the k-th measurement, Δt k is the time required for the k-th measurement.
5. The method for calculating the average temperature rise of the winding of an oil-immersed transformer based on respiratory characteristic parameters according to claim 1, characterized in that In step S3, the calculation of the dynamic impedance coefficient of the transformer, the formula is shown as follows: In the formula, Z0 is the dynamic impedance coefficient at room temperature of 298K, Z is the dynamic impedance coefficient at the current temperature T, μ is the aerodynamic viscosity of the gas at the current temperature T, μ0 is the aerodynamic viscosity of the gas at room temperature of 298K. Both μ and μ0 are obtained based on the Sutherland formula using the temperature. P and P0 are the differential pressures under the actual working condition and the rated working condition respectively, ε is the porosity of the silica gel tank, and L is the equivalent length of the air flow path.
6. The method for calculating the average temperature rise of the winding of an oil-immersed transformer based on respiratory characteristic parameters according to claim 1, wherein In step S3, the calculation of the life attenuation coefficient of the breather silica gel, the formula is shown as follows: Wherein, η is the life attenuation coefficient of the respirator silica gel, m is the number of cycles of the silica gel, S is the equivalent cross-sectional area of the air flow path of the respirator, H in is the humidity of the incoming gas, and H out is the humidity of the outgoing gas.
7. A method for calculating the average temperature rise of the winding of an oil-immersed transformer based on respiratory characteristic parameters according to claim 1, characterized in that In step S4, the calculation of the average temperature rise of the transformer winding, the formula is shown as follows: In the formula, ΔT is the average temperature rise of the winding, M is the mass of the transformer oil, ρ is the density of the transformer oil, and α is the expansion coefficient of the transformer oil. Where k is a dimensionless proportional correction coefficient, k = 22069.29; T C is the temperature correction coefficient, T C = 260.74 K.